WowAce

Reports in raid chat whenever a raid member "fails." /EnsidiaFails to configure.

Loot Distribution System

Tracks skill and tradeskill costs and progressions, as well as trainer locations.

Keeps track of time played and rested XP across your characters.

Rebuff yourself with the mousewheel.

Auto and random summon highly customizable for your pets and mounts, with Data Broker support.

Detects specific CDs and spellcasts

StarVisuals displays various data visualizations

A helper addon for the achievements "Let It Snow", "Fistful of Love", "Shake Your Bunny-Maker", "Check Your Head", and "Turkey Lurkey"

Reduces interface tedium by doing the little things for you.

A jukebox for playing wow embedded music.

Automatic Refilling of User Defined Items

LDB data source for currency flow

GonffBar

Auto roll greed, need, pass or manually roll on items.

Omnibus

Role playing AddOn that shows extra information about characters as entered by the player.

Threat-2.0

Regain that wasted space!

Dynamic item DKP calculation